Various devices and methods for recording the pressures of fluid media, such as of gases and liquids, are available in the related art. The measured quantity of the pressure is a nondirectional force that acts in all directions and occurs in gases and liquids. Dynamically and statically acting pickups or sensor elements are used to measure pressures. Dynamically acting pressure sensors are only used for measuring pressure pulsations in gaseous or liquid media. The pressure measurement can be performed directly, by membrane deformation, or by using a force sensor.
In particular, to measure very high pressures, it would suffice to simply expose the medium to an electrical resistance, because, to a greater or lesser degree, all conventional resistors exhibit a pressure dependency. However, it proves to be difficult to thereby simultaneously suppress the dependency of the resistors on temperature and the pressure-tight leading through of the electrical connections thereof out of the pressure medium.
Therefore, for signal acquisition purposes, the most common method for recording pressure initially employs a thin membrane as a mechanical intermediate stage that is exposed on one side to the pressure and deflects to a greater or lesser degree as a function of the pressure. The thickness and diameter thereof can be adapted within a very wide range to the particular pressure range. Low-pressure measuring ranges lead to comparatively large membranes which can deform within the range of from 0.1 to 1 mm. However, high pressures require thicker, low-diameter membranes which, for the most part, only deform by a few micrometers. Pressure sensors of this kind are described in, for example, Konrad Reif (publisher): Sensoren im Kraftfahrzeug [Sensors in the Motor Vehicle], 1st edition, 2010, pp. 80-82 and 134-136.
German Patent Application No. DE 10 2008 054 382 A1 describes a pressure sensor module that includes a pressure sensor chip for determining the pressure of a measuring medium, an adapter for transmitting pressure to the pressure sensor chip, a connector part contacted by the pressure sensor chip, as well as fastening means for fixedly securing the pressure sensor module in a receiving opening of a wall.
A separate sensor module having a measuring element is used in pressure sensors of this kind. For various media requirements, an application to the rear side of the measuring element or a gel passivation is possible.
In spite of the improvements brought about by these pressure sensors, there is still a potential to optimize known pressure sensors. Thus, when working with adhesively bonded sensor elements of existing pressure sensors, the media resistance provided by the rear-side application is good, but is problematic because of water and particles that can settle on the membrane. The pressure range is limited, and soldered connections are susceptible to corrosion. In the case of the gel passivation, the medium can be diffused by the gel and thereby change the protective action or affect the measurement signals due to various chemical and/or physical processes.